Characteristics of nitrite and nitrate in situ denitrification in landfill bioreactors

The objective of this research was to investigate the macroscopical effect of high concentration nitrite and nitrate denitrification on waste decomposition and to evaluate the kinetics of NO3-–N and NO2-–N removal. Two reactors loaded fresh refuse were fed 4000 mg NO3-–N/L or 4000 NO2-–N/L every 48 h, respectively. Results showed that NO3-–N addition was more effective on promotion of the waste degradation process as compared to NO2-–N addition. In the initial stage, NOx-–N removal was mainly contributed by adsorption rather than denitrification. NOx-–N reduction rate data obtained from microcosm experiment were fit to Monod kinetics, with specific removal rates of 1.625 mg NO3-–N/(g dry waste d) and 1.125 mg NO2-–N/(g dry waste d) and nitrogen removal half-saturation constants of 1250.5 NO3-–N/L and 125.5 NO2-–N/L, respectively.